Electric machine cooling system and method

ABSTRACT

Embodiments of the invention provide an electric machine module and a method for cooling an electric machine. The electric machine module includes the electric machine including a stator with stator end turns and a housing enclosing the electric machine. An inner wall of the housing defines a machine cavity. The electric machine module also includes a cover coupled to the housing and extending radially inward into the machine cavity. The cover and the stator end turns define a stator cavity which is in fluid communication with the machine cavity.

BACKGROUND

Hybrid vehicles offer an opportunity for vehicle drivers to engage inenvironmentally-conscious behavior because of hybrids' improved fueleconomy and reduced emissions. Hybrid vehicles combine traditionalinternal combustion engines with an electro-mechanical transmission.Electric motors located within the electro-mechanical transmissionprovide energy to propel the vehicle, reducing the need for energyprovided by the internal combustion engine, thereby increasing fueleconomy and reducing emissions.

As with any electric machine, the hybrid transmission's electric motorrejects some energy in the form of heat. Efficient removal of heat fromthe electric motor can improve the lifespan of the electric machine aswell as improve the electric machine's operating efficiency.

SUMMARY

Some embodiments of the invention provide an electric machine modulecapable of being cooled by a coolant. The electric machine module caninclude an electric machine including a stator with stator end turns anda housing enclosing the electric machine. An inner wall of the housingcan define a machine cavity. The electric machine module can alsoinclude a cover coupled to the housing and extending radially inwardinto the machine cavity. The cover and the stator end turns can define astator cavity which is in fluid communication with the machine cavity.

In some embodiments, the electric machine module can include an electricmachine including a stator with stator end turns and a rotor. Theelectric machine module can also include a housing enclosing theelectric machine. An inner wall of the housing can define a machinecavity. The electric machine module can further include a cover coupledto the housing and extending radially inward into the machine cavity,and an agitator ring operatively coupled to the rotor and extendingsubstantially outward along at least a portion of an axial length of thestator end turns. The cover, the agitator ring, and the stator end turnscan define a stator cavity, the stator cavity being in fluidcommunication with the machine cavity.

Some embodiments of the invention provide a method for cooling anelectric machine. The method can include providing the electric machineincluding a rotor with generally opposing end faces and a statorsubstantially circumscribing the rotor and including stator end turns.The method can also include substantially enclosing at least a portionof the electric machine substantially within a housing and defining atleast a portion of a machine cavity with an inner wall of the housing.The method can further include providing a cover coupled to the housingand extending radially inward into the machine cavity, introducing acoolant into the machine cavity, and concentrating the coolant near thestator end turns using the cover in order to cool the stator end turns.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of an electric machine module accordingto one embodiment of the invention.

FIG. 2 is a partial cross-sectional view of an electric machine with anagitator member, according to one embodiment of the invention.

FIG. 3 is another cross-sectional view of the electric machine moduleaccording to one embodiment of the invention.

FIG. 4 is a perspective view of a portion of the electric machine ofFIG. 2.

FIG. 5 is a partial perspective view of a portion of the electricmachine of FIG. 2.

FIG. 6 is a cross-sectional view of the electric machine of FIG. 2.

FIG. 7A is a cross-sectional view of an electric machine moduleaccording to another embodiment of the invention.

FIG. 7B is a cross-sectional view of an electric machine moduleaccording to yet another embodiment of the invention.

DETAILED DESCRIPTION

Before any embodiments of the invention are explained in detail, it isto be understood that the invention is not limited in its application tothe details of construction and the arrangement of components set forthin the following description or illustrated in the following drawings.The invention is capable of other embodiments and of being practiced orof being carried out in various ways. Also, it is to be understood thatthe phraseology and terminology used herein is for the purpose ofdescription and should not be regarded as limiting. The use of“including,” “comprising,” or “having” and variations thereof herein ismeant to encompass the items listed thereafter and equivalents thereofas well as additional items. Unless specified or limited otherwise, theterms “mounted,” “connected,” “supported,” and “coupled” and variationsthereof are used broadly and encompass both direct and indirectmountings, connections, supports, and couplings. Further, “connected”and “coupled” are not restricted to physical or mechanical connectionsor couplings.

The following discussion is presented to enable a person skilled in theart to make and use embodiments of the invention. Various modificationsto the illustrated embodiments will be readily apparent to those skilledin the art, and the generic principles herein can be applied to otherembodiments and applications without departing from embodiments of theinvention. Thus, embodiments of the invention are not intended to belimited to embodiments shown, but are to be accorded the widest scopeconsistent with the principles and features disclosed herein. Thefollowing detailed description is to be read with reference to thefigures, in which like elements in different figures have like referencenumerals. The figures, which are not necessarily to scale, depictselected embodiments and are not intended to limit the scope ofembodiments of the invention. Skilled artisans will recognize theexamples provided herein have many useful alternatives and fall withinthe scope of embodiments of the invention.

FIG. 1 illustrates an electric machine module 10 according to oneembodiment of the invention. The machine module 10 can include anelectric machine 12 and a housing 14. The electric machine 12 can bedisposed within a machine cavity 16 defined at least partially by aninner wall 18 of the housing 14. The electric machine 12 can include arotor 20, a stator 22 substantially circumscribing the rotor 20, statorend turns 24, and bearings 26, and can be disposed about a main outputshaft 28. In some embodiments, the electric machine 12 can also includea rotor hub 30 or can have a “hub-less” design (not shown).

The electric machine 12 can be, without limitation, an electric motor,such as a hybrid electric motor, an electric generator, or a vehiclealternator. In one embodiment, the electric machine 12 can be aninduction belt-alternator-starter (BAS). In another embodiment, theelectric machine 12 can be a High Voltage Hairpin (HVH) electric motorfor use in a hybrid vehicle.

Components of the electric machine 12 such as, but not limited to, thestator end turns 24, the rotor 20, and the rotor hub 30 can generateheat during operation of the electric machine 12. These components canbe cooled to enhance the performance of and increase the lifespan of theelectric machine 12.

As shown in FIG. 1, the rotor 20 can include generally opposing endfaces 32, 34. A balance ring 36 can be coupled to the rotor 20 and/orthe rotor hub 30 at a location proximal to the generally opposing endfaces 32, 34. In some embodiments, the balance ring 36 can be coupled tothe rotor hub 30 using threads, a plurality of threaded fasteners, afriction fitting, welding, or another conventional coupling manner sothat the balance ring 36 can rotate substantially synchronously with therotor 20 and the rotor hub 30 during operation of the electric motor 12.In addition, the balance ring 36 can be “staked” to a lip 35 on an innerdiameter of the rotor hub 30 and a portion of the balance ring 36 can beheat pressed to a lamination stack of the rotor 20 (e.g., for axialsupport), as shown in FIG. 3. Additional components, such as steelinsert pieces, can also be used to help clamp the balance ring 36 to therotor hub 30 around the lip 35. The balance ring 36 can extend axiallyfrom the rotor hub 30 into the machine cavity 16 and can providestability for the rotor 20 and rotor hub 30 during operation of theelectric machine 12. In one embodiment, the balance ring 36 comprisescast aluminum.

In other embodiments, such as those including the hub-less design, thebalance ring 36 can be coupled to the rotor 20 proximal to the generallyopposing end faces 32, 34, as shown in FIG. 2. The balance ring 36 canbe coupled to the rotor 20 using threads, a plurality of threadedfasteners, a friction fitting, welding, or another conventional couplingmanner so that the balance ring 36 can rotate substantiallysynchronously with the rotor 20 during operation of the electric motor12. The balance ring 36 can provide stability for the rotor 20 duringoperation of the electric machine 12. In either the hub-less design orembodiments including the rotor hub 30, the balance ring 36 can beoperatively coupled to the rotor 20 (i.e., through direct coupling orcoupling via the rotor hub 30) due to the fact that it can rotate withthe rotor 20 during operation of the electric machine.

In some embodiments, an agitator member 38 can be a ring-shaped membercoupled to the rotor 20, the rotor hub 30, and/or the balance ring 36proximal to the generally opposing end faces 32, 34. More specifically,at least a portion of the agitator member 38 can be coupled to the rotor20, the rotor hub 30 and/or the balance ring 36 such that the agitatormember 38 synchronously rotates with the rotor 20 and the rotor hub 30when the electric machine 12 is in operation. The agitator member 38 canbe coupled to the rotor 20, the rotor hub 30, and/or the balance ring 36using threads, one or more threaded fasteners, a friction fitting,welding, or another conventional coupling manner. In one embodiment, theagitator member 38 can be staked to a lip (not shown) on the innerdiameter of the rotor hub 20 and further axial support can be providedby heat pressing a portion of the agitator member 34 in a laminationstack surrounding the rotor 20. In another embodiment, the agitatormember 38 can be cast as part of the rotor 20 during rotor fabricationso that the agitator member 38 and the rotor 20 are integral. In yetanother embodiment, the agitator member 38 can be integral with thebalance ring 36. The agitator member 38 can extend axially away from therotor 20 and/or the rotor hub 30 into the machine cavity 16.

In some embodiments, the agitator member 38 can be coupled to the rotor20 and/or the rotor hub 30 with or without the balance ring 36. If thebalance ring 36 is present, an axial length of the agitator member 38can be substantially equal to or longer than an axial length of thebalance ring 36. For example, in one embodiment, at least a portion ofthe agitator member 38 can extend axially past the balance ring 36(i.e., axially away from the rotor 20). In addition, the agitator member38 can extend substantially parallel to the stator end turns 24 along atleast a portion of an axial length of the stator end turns 24. In someembodiments, the agitator member 38 can extend substantially axiallyoutward about as far as the stator end turns 24. In other embodiments,the axial length of the agitator member 38 can be shorter than or longerthan the axial length of the stator end turns 24.

In either the hub-less design or embodiments including the rotor hub 30,the agitator member 38 can be operatively coupled to the rotor 20 (i.e.,through direct coupling or coupling via the rotor hub 30 or the balancering 36) due to the fact that it can rotate with the rotor 20 duringoperation of the electric machine.

In some embodiments, the agitator member 38 and the balance ring 36 canbe an integral structure, as described above. In other embodiments, thebalance ring 36 and the agitator member 38 can comprise two or moreindependent components. The balance ring 36 and the agitator member 38can be fabricated from aluminum, steel, stainless steel, or othersimilar materials. In some embodiments, the agitator member 38 can beoriented so that it extends substantially parallel to an axis ofrotation 40 of the rotor 20. In other embodiments, the agitator member38 can be oriented in either a positive or negative direction relativeto the rotor's axis of rotation 40.

In addition, the agitator member 38 can include a radially distalsurface 42 and a radially proximal surface 44. The radial location of aboth the radially distal surface 42 and the radially proximal surface 44can vary. For example, the radially distal surface 42 can have a shorterradius than the rotor 20 (e.g., by a length “x”, as shown in FIG. 4) orcan have a radius equal to a radius of the rotor 20 (as shown in FIG.2). In some embodiments, the radially distal surface 42 can have ashorter radius than the radius of the rotor 20 to provide substantialradial separation between an underside of the stator end turns 24 andthe agitator member 38.

In some embodiments, as shown in to FIG. 4, a plurality of struts 46 canprovide support for the agitator member 38. The plurality of struts 46can be cast or otherwise formed in the agitator member 38 so that thestruts 46 and the agitator member 38 are a unitary body.

In some embodiments, at least a portion of the housing 14 can include aplurality of coolant apertures 48. The coolant apertures 48 can be influid communication with, for example, a coolant jacket 50 locatedsubstantially around the electric machine 12 (e.g., within an inner wallof the housing 14 or along the outside or inside of the housing 14substantially surrounding an outer diameter of the stator 22) and themachine cavity 16. A coolant, such as transmission fluid, ethyleneglycol, an ethylene glycol/water mixture, water, oil, or a similarsubstance, can originate from a fluid source (not shown), flowthroughout the coolant jacket 50, and can be dispersed through thecoolant apertures 48 into the machine cavity 16.

In one embodiment, the coolant apertures 48 can be positioned so thatthe coolant can be dispersed onto the stator end turns 24, as shown inFIG. 2. After reaching the stator end turns 24, the coolant can receiveheat energy from the stator end turns 24, which can result in cooling ofthe electric machine 12. Some of the coolant can be dispersed past thestator end turns 24 or, for example, splash or drip from the stator endturns 24 onto the radially distal surface 42 of the agitator member 38.In addition, some of the coolant that comes in contact with the statorend turns 24 can continue to flow toward the radially distal surface 42.As the coolant reaches the radially distal surface 42, the coolant canbe substantially radially slung back outward on to the stator end turns24 due to the rotation of the agitator member 38 in synchronicity withthe rotor 20. The process of radially slinging the coolant toward thestator end turns 24 can serve to recycle the coolant, and thus, maximizecooling potential of the coolant.

In some embodiments, the process of radially slinging the coolant backtoward the stator end turns 24 using the agitator member 38 can beconsidered a “multiple-pass” method of cooling, as the coolant can reachthe stator end turns 24 multiple times to provide additional cooling.Conventional electric machines use a “single-pass” method of coolingwhere the coolant only reaches the stator end turns 24 once and then isdischarged away from the electric machine 12 without further coolingbenefits. In addition, the single-pass method only permits the coolantto reach radially outer surfaces of the stator ends turns 24, whereasthe multiple-pass method allows coolant to be slung back towardsradially inner surfaces of the stator end turns 24. As a result, themultiple-pass cooling method allows the coolant to reach both theradially outer surface as well as the radially inner surface of thestator end turns 24, and thus, provides enhanced cooling.

In one embodiment, as shown in FIGS. 4, 5, and 6, the radially distalsurface 42 can include a textured surface 52. The textured surface 52can have different textures such as scalloping, ribbing, ridging, etc.In some embodiments, the textured surface 52 can be asymmetric in shapeto increase the force with which the coolant is slung. In anotherembodiment, the radially distal surface 42 can lack texture and caninclude a substantially planar or smooth surface.

In comparison to conventional balance rings, the agitator member 38,including the textured surface 52 or the substantially planar surface,can enhance radial slinging of the coolant because it provides moresurface area to receive the coolant. Also, because the agitator member34 can synchronously rotate with the rotor 20 and/or the rotor hub 30,centrifugal force can force the coolant away from the agitator member 38so that the coolant can be dispersed onto the stator end turns 24. Inone embodiment, the amount and shape of texturing on the texturedsurface 52 can be selected to provide a desired amount of coolingwithout slinging the coolant at velocities which can possibly erode thestator end turns 24. In addition, compared to conventional balancerings, the agitator member 38 can further increase air circulationwithin the machine cavity 16, and thus, enhance electric machinecooling, because its larger mass, relative to a balance ring alone, candisplace more air when the agitator member 38 is in motion. In oneembodiment, the textured surface 52 can be shaped similar to pump or fanvanes to help increase air circulation and/or increase radial slingingof the coolant.

In some embodiments, the agitator member 38 can include a plurality ofagitator channels 54. As shown in FIGS. 2 and 5, the agitator channels54 can extend radially through the agitator member 38. The plurality ofagitator channels 54 can extend through any desired radial length of theagitator member 38, such as a full length of the agitator member 34 or aportion of the full length of the agitator member 38. The agitatorchannels 54 can be positioned at nearly any distance along the axiallength of the agitator member 38 (e.g., more proximal to the rotor 20,centrally along the axial length, or more distal from the rotor 20). Forexample, as shown in FIG. 5, the plurality of agitator channels 54 canbe positioned axially distal from the rotor 20. The location of each ofthe plurality of agitator channels 54 can be symmetric or asymmetricalong the agitator member 38 (i.e., not each agitator channel may bepositioned at the same distance along the axial length of the agitatormember 38).

Additionally, any number of agitator channels 54 can be included in theagitator member 38, or in attachments to the agitator member 38. In someembodiments, as shown in FIG. 5, each of the plurality of agitatorchannels 54 can be circular in shape. In other embodiments, the agitatorchannels 54 can have similar or different shapes, including circular,square, rectangle, oval, and/or other shapes. Also, the plurality ofagitator channels 54 can include similar or varying radii or diameters.The agitator channels 54 can be of sufficient size to allow passage of aportion of the coolant through the agitator channels 54, as describedbelow. The agitator channels 54 can be sized and positioned so thatanother portion of the coolant that reaches the agitator member 38 cancontinue to be substantially radially slung toward the stator end turns24.

In some embodiments, an additional volume of the coolant also can beexpelled near the rotor hub 30, for example, from a base of the rotorhub 30 or from the main input shaft 28. The coolant expelled near therotor hub 30 can flow radially outward toward the housing 12 (e.g., dueto centrifugal force). A portion of the coolant can reach the radiallyproximal surface 44 of the agitator member 38, and the agitator channels54 can provide a pathway for the coolant to flow between the radiallyproximal surface and the radially distal surface. More specifically, thecoolant 50 flowing radially outward onto the agitator member 38 can flowthrough the agitator channels 54 so that it reaches the radially distalsurface 42 and is substantially radially slung toward the stator endturns 24, or at least concentrated near the stator end turns 24. Theadditional volume of coolant can further aid in cooling the electricmachine 12, including the stator end turns 24.

FIGS. 7A and 7B illustrate the electric machine module 10 according toanother embodiment of the invention. As shown in FIG. 7A, a cover 56 canbe coupled to the inner wall 18 and at least partially surround thestator end turns 24 so that the cover 56 and each of the stator endturns 24 define a stator cavity 58 around the stator end turns 24. Thestator cavity 58 can be in fluid communication with the machine cavity16. The cover 56 can also substantially surround the stator 22. Forexample, FIG. 7A illustrates the cover entirely surrounding the stator22 as well as partially surrounding the stator end turns 24 (e.g., as anintegral stator housing ring and cover assembly). In some embodiments,additional caps (not shown) can enclose the cover 56 within the housing14. In other embodiments, the cover 56 can be a part of the housing 14(e.g., extending from the inner wall 18 on either end of the stator 22to partially surround the stator end turns 24).

The cover 56 can extend a desired radial distance from the inner wall 18and, in some embodiments, can turn back inward axially, as shown inFIGS. 7A and 7B. The cover 56 can also be positioned a desired axialdistance from the housing 14. The desired distances can be uniform orvary along radial portions of, or along the circumference of, theelectric machine 12 and, as a result, the stator cavity 58 can beuniform or vary in size along the radial portions. In addition, in someembodiments, the stator cavity 58 may not extend around the entire 360degrees of the stator end turns 24 (i.e., some radial portions of thestator end turns 24 are not surrounded by the cover 56).

The cover 56 can comprise plastic, aluminum, steel, a polymericmaterial, or a similar material. In some embodiments, the size of thestator cavity 58 can vary depending on the dielectric properties of thecoolant and the materials from which the cover 56 are fabricated ordepending on its radial position within the electric machine module 10.In one embodiment, the size of the stator cavity 58 can be reduced bycoating an area of the cover 56 closest to the stator end turns 24 witha material of high dielectric strength, such as an epoxy material 60, asshown in FIG. 3. In another embodiment, an upper portion of the electricmachine module 10 can include a substantially larger stator cavity 58than a lower portion of the electric machine module 10.

In some embodiments, the cover 56 can be coupled to the inner wall 18 bypress fitting, friction fitting, threaded fasteners, or a similarcoupling manner. In addition, the cover 56 can comprise one or moreparts, where some parts of the cover 56 are integral with the inner wall18 and other parts of the cover are coupled to the inner wall 18. Thestator cavity 58 can receive the coolant from the cooling jacket 50 andthe coolant apertures 48 (similar to that shown in FIG. 2), or from acooling jacket 59 formed between the cover 56 and the inner wall 18through coolant apertures 61 of the cover 56. The cooling jacket 59 canreceive the coolant from a feed port 62, as shown in FIGS. 6-7B, influid communication with the fluid source. After the coolant flows intothe stator cavity 58, the cover 56 can help concentrate the flowingcoolant within the stator cavity 52 so that the coolant can remain incontact with or near the stator end turns 24 for a prolonged time periodin order to help transfer more heat energy. The coolant can eventuallydisperse out of the stator cavity 58 toward the machine cavity 16.Compared to conventional cooling systems, the cover 56 can greatlyenhance cooling of the stator end turns 24 because the cover 56 canprevent at least some of the coolant from quickly dispersing away fromthe stator end turns 24 and can help concentrate the coolant near theheat energy-radiating stator end turns 24.

In one embodiment, as shown in FIG. 7B, the stator cavity 58 can bedefined by the cover 56 and the stator end turns 24 as well as theagitator member 38. The stator cavity 58 can be in fluid communicationwith the machine cavity 16, as described above. When the coolant entersthe stator cavity 58, the coolant can flow onto the stator end turns 24and can be concentrated within the stator cavity 58 by the presence ofthe cover 56. In addition, when the coolant flows toward the agitatormember 38, it can be radially slung back toward the stator end turns 24and the cover 56 where it can once again become concentrated around thestator end turns 24. The combination of the cover 56 and the agitatormember 38 can synergistically improve cooling efficiency by applying andrecycling the coolant near and around the stator end turns 24.

Because the stator cavity 58 can be in fluid communication with themachine cavity 16 in some embodiments, some of the coolant can flow intothe machine cavity 16 while a significant portion of the coolant canremain within the stator cavity 58. In some embodiments, further coolingcan be achieved using an additional volume of coolant expelled from nearthe rotor hub 30. The additional volume of coolant can flow radiallyoutward, through some of the plurality of agitator channels 52, andtoward the stator cavity 58 so that it can be applied and reapplied tothe stator end turns 24. The additional flow of coolant can lead to moreefficient heat energy transfer because of exchange of the coolant andrepeated recycling of the coolant near the stator end turns 24.

After flowing over the electric machine components, the coolant can poolat or near a bottom portion of the housing 12 (e.g., by flowing in themachine cavity 16 outside of the cover 56 or through drain ports 64 ofthe cover 56). A drain (not shown) can be located at or near the bottomportion in order permit removal of pooling coolant from the housing 12.The drain can be coupled to an element which can remove the heat energyfrom the drained coolant, such as a radiator or other suitable heatexchanger, so that it can be circulated back to the fluid source.

It will be appreciated by those skilled in the art that while theinvention has been described above in connection with particularembodiments and examples, the invention is not necessarily so limited,and that numerous other embodiments, examples, uses, modifications anddepartures from the embodiments, examples and uses are intended to beencompassed by the claims attached hereto. The entire disclosure of eachpatent and publication cited herein is incorporated by reference, as ifeach such patent or publication were individually incorporated byreference herein. Various features and advantages of the invention areset forth in the following claims.

1. An electric machine module capable of being cooled by a coolant, theelectric machine module comprising: an electric machine including astator with stator end turns; a housing enclosing the electric machine,an inner wall of the housing defining a machine cavity, the housingfurther comprising a coolant jacket circumscribing at least a portion ofthe electric machine and at least one coolant aperture being positionedsubstantially adjacent to at least a portion of the stator end turns,the coolant jacket capable of containing a volume of the coolant, the atleast one coolant aperture being configured to disperse at least aportion of the coolant from the coolant jacket into a stator cavity; anda cover coupled to the housing and extending radially inward into themachine cavity, the cover and the stator end turns defining the statorcavity, the stator cavity being in fluid communication with the machinecavity, wherein the cover is configured and arranged to concentrate atleast a portion of the coolant within the stator cavity substantiallyaround the stator end turns when the coolant enters the machine cavityfrom the at least one coolant aperture.
 2. The electric machine moduleof claim 1, wherein the cover at least partially surrounds the statorend turns.
 3. The electric machine module of claim 1, wherein the coverentirely surrounds the stator.
 4. The electric machine module of claim1, wherein the cover extends axially inward to at least partiallysurround the stator end turns.
 5. The electric machine module of claim1, wherein the cover is located an axial distance away from axial endsof the housing, wherein the axial distance varies along a circumferenceof the housing.
 6. The electric machine module of claim 1, wherein thecover comprises at least one of plastic, aluminum, steel and a polymericmaterial.
 7. The electric machine module of claim 1 and furthercomprising an epoxy material filled within at least a portion of thestator cavity between the stator end turns and the cover.
 8. An electricmachine module capable of being cooled by a coolant, the electricmachine module comprising: an electric machine including a stator withstator end turns and a rotor; a housing enclosing the electric machine,an inner wall of the housing defining a machine cavity; a coolant jacketat least partially circumscribing a portion of the stator, the coolantjacket capable of containing a volume of the coolant; a plurality ofcoolant apertures being configured to guide a portion of the coolantfrom the coolant jacket into a stator cavity adjacent to at least aportion of stator end turns; a cover coupled to the housing andextending radially inward into the machine cavity; and an agitatormember operatively coupled to the rotor and extending substantiallyoutward along at least a portion of an axial length of the stator endturns, the cover, the agitator member, and the stator end turns definingthe stator cavity, the stator cavity being in fluid communication withthe machine cavity, and the agitator member being configured to radiallyreturn a portion of the coolant that flows past the stator end turnsback to the stator end turns for additional cooling.
 9. The electricmachine module of claim 8, wherein the electric machine further includesa rotor hub, and the agitator member is coupled to the rotor by therotor hub.
 10. The electric machine module of claim 8, wherein theagitator member includes a radially distal surface and a radiallyproximal surface, the radially distal surface comprising a texturedsurface.
 11. The electric machine module of claim 8, wherein an axiallength of the agitator member is one of less than, more than, and aboutthe same as the axial length of the stator end turns.
 12. A method forcooling an electric machine comprising: providing the electric machineincluding a rotor with generally opposing end faces, and a statorsubstantially circumscribing the rotor and including stator end turns;substantially enclosing at least a portion of the electric machinewithin a housing, defining at least a portion of a machine cavity withan inner wall of the housing; circumscribing at least a portion of thestator with a coolant jacket, the coolant jacket capable of containing avolume of a coolant; disposing a plurality of coolant apertures througha portion of the inner wall, the plurality of coolant apertures beingconfigured to introduce the coolant from the coolant jacket into themachine cavity; and providing a cover coupled to the housing andextending radially inward into the machine cavity, the cover beingconfigured and arranged to concentrate at least a portion of the coolantintroduced into the machine cavity through the plurality of coolantapertures near the stator end turns in order to cool the stator endturns.
 13. The method of claim 12 and further comprising coupling anagitator member to the rotor adjacent to the generally opposing endfaces, the agitator member being configured to return a portion of thecoolant that flows past the stator end turns back to the stator endturns for additional cooling.
 14. The method of claim 13 wherein thecover and the agitator member are configured to concentrate at least aportion of the coolant.
 15. The method of claim 13 wherein the electricmachine is configured so that another volume of coolant is introducedinto the machine cavity from a position radially inward from the statorend turns so that the coolant is dispersed radially outward toward thestator end turns.
 16. The method of claim 15 and further comprisingproviding agitator channels through the agitator member to direct thecoolant toward the stator end turns.
 17. The method of claim 12 whereinthe plurality of coolant apertures are positioned radially adjacent tothe stator end turns.
 18. The method of claim 17 and further comprisingpositioning the coolant apertures to direct the coolant toward thestator end turns.